Specific Energy Costs of Grinding Wood when Preparing a Composite for 3D-Printing

Abstract

The Northwestern Federal District is a region of Russia rich in a variety of wood species. The properties of wood in this region differ significantly from the properties of wood grown in other countries or in the eastern part of Russia, which leads to differences in energy costs of grinding wood. The aim of this research has been to estimate the specific energy costs of grinding wood to the state of wood flour, which will be used as the basis for wood polymer composite consumables in additive technologies. Wood flour has been obtained by grinding wood in a laboratory disk mill, repeatedly reducing the particle size. The granulometric composition has been analyzed for beech, oak, larch, alder and pine wood at 1, 3, 5 and 10 grinding cycles. Particle sizes have been determined by analyzing images obtained using an optical microscope and processed in the ImageJ graphic program. The specific energy costs of grinding have been estimated by recording the power with a wattmeter every second with repeated feeding of wood flour for the known mill productivity. When calculating the specific energy consumption, the moisture content of each wood species has been taken into account, as well as productivity losses associated with the adhesion of wood particles to the working surfaces of the dispersing set and the inner area of the disk mill body. The research has revealed a relationship between the specific energy costs and the particle size of wood flour obtained from various wood species. Regression analysis of curves corresponding to different wood species has made it possible to obtain exponential and power-law dependencies that do not contradict the fundamental theoretical laws of grinding solid particles. Based on these results, pine wood flour has been recognized as the most energy-efficient option. The established dependencies can be used to predict the specific energy consumption for grinding beech, oak, larch, alder and pine wood in disk mills.